A cerebral aneurysm is a localized weak spot on a blood vessel in the brain that balloons outward, often resembling a berry. The stretched, thin wall of the aneurysm can rupture, leading to a life-threatening hemorrhagic stroke. Treatment focuses on isolating the aneurysm from normal blood circulation to prevent or stop bleeding. This is achieved through either an open surgical procedure or a less invasive, catheter-based approach.
The Procedure Requiring Open Surgery
The procedure that requires a craniotomy is Surgical Clipping. This microsurgery is performed by a neurosurgeon to physically seal off the aneurysm from its parent artery. The craniotomy involves temporarily removing a section of the skull bone to allow direct access to the brain.
Once the patient is under general anesthesia, the surgeon makes an incision in the scalp and removes a piece of the skull to create a “bone flap.” The brain tissue is then gently separated, often using a high-powered operating microscope, to locate the artery and the aneurysm. The goal is to isolate the aneurysm without damaging surrounding tissue or small perforating arteries.
After the aneurysm is carefully dissected, the surgeon places a small, specialized metal clip, usually made of titanium, across the neck or base of the aneurysm. This clip permanently blocks blood flow into the bulging sac. The clip remains in place for life, causing the aneurysm sac to clot off and eventually shrink.
The bone flap is then secured back into place with small plates and screws before the scalp incision is closed. Clipping offers a high rate of complete and immediate occlusion, meaning the aneurysm is definitively sealed off during the procedure. It is a highly effective, long-established treatment that directly addresses the weakened vessel wall.
The Minimally Invasive Treatment Alternative
In contrast to surgical clipping, most modern treatments use endovascular techniques that do not require a craniotomy. These methods access the aneurysm from within the blood vessel system, offering a less invasive alternative. The procedures involve inserting a catheter into an artery, typically in the groin or wrist, and guiding it through the vascular network up to the brain.
One common approach is Endovascular Coiling, where a microcatheter is maneuvered into the aneurysm sac. Very thin, soft platinum coils are deployed through the catheter to fill the aneurysm. Once packed inside, these coils promote clotting within the aneurysm, effectively sealing it off from the circulating blood flow.
Flow Diversion
Another technique is Flow Diversion, which treats the aneurysm by reconstructing the parent artery. A specialized, densely braided stent, known as a flow diverter, is placed across the neck of the aneurysm. This device redirects the blood flow away from the aneurysm sac, promoting healing of the arterial wall and causing the aneurysm to thrombose and shrink. Both coiling and flow diversion rely on internal access, avoiding the need for an open skull procedure and often resulting in a quicker recovery time than traditional surgery.
How Doctors Choose the Right Procedure
The decision between open surgical clipping and an endovascular approach is highly individualized, involving a multidisciplinary team of specialists. The choice is based on a complex evaluation of the patient’s overall health and specific characteristics of the aneurysm. Patient health, including age and the presence of other medical conditions, plays a role, as the endovascular option is often safer for older or higher-risk patients.
Aneurysm location is a significant factor. Those located on the middle cerebral artery are often more accessible and better suited for surgical clipping. Aneurysms in deeper or posterior circulation areas, such as the basilar artery, are frequently treated endovascularly due to the difficulty of surgical access.
Aneurysms with a wide neck are generally more challenging for coiling alone, making clipping or flow diversion potentially more effective. Whether the aneurysm has ruptured or remains unruptured also influences the decision. A ruptured aneurysm sometimes requires clipping to simultaneously remove the blood clot and secure the vessel. Ultimately, the selection process weighs the long-term effectiveness of complete aneurysm obliteration against the immediate risks and recovery time associated with each procedure.